I noticed I have a strange problem... when playing live, my right hand gets stiff, and I find myself in great troubles playing fast parts... when I play with fingers, the result is I hit the strings very hard, using a pick, I give a death grip to the pick and it tends to slip... and my hand gets fatigued very fast... I also noticed the problem is related to volume... the higher the volume we're playing at, the more my hand gets stiff.... this happens also when I am nervous, for example when I know that I am playing something really difficult and something could get wrong... and the situation gets worse when it's cold and I have less control on my hands... have you ever encountered this kind of problem? how could I fix it? just relaxing??